If you have tabular data with columns like countyName, indicatorName, indicatorValue, indicatorMonth, indicatorYear, then the typical way to encode this is as an n-ary relation. See Defining N-ary Relations on the Semantic Web for more details, but the general idea is that you'd do something like this:
_:record72 rdf:type :WaterQualityRecord ;
countryName "some country" ;
indicatorName "some indicator" ;
indicatorValue 42 ;
indicatorMonth 9 ; # e.g., for September
indicatorYear 2013 . # e.g., for 2013
_:record73 rdf:type :WaterQualityRecord ;
countryName "some other country" ;
indicatorName "some other indicator" ;
indicatorValue 89 ;
indicatorMonth 3 ; # e.g., for March
indicatorYear 2014 . # e.g., for 2014
Then ordering by date is a simple matter of ordering first by indicatorYear and then by indicatorMonth. You might also consider combining those properties into a single property whose value is an xsd:dateTime, but that's not quite as important.